Worries over Egypt, and concerns over shipments through the Suez canal, yesterday pushed the price of oil above $100 a barrel. But there's more to the story than that. The recent stance of Opec, the cartel of oil-producing countries, must also be highlighted.

Opec has said consistently that $70-$80 a barrel is its preferred price range but it has done next to nothing to support this language with action. Production quotas were not increased sharply when the $90 mark was passed.

Nor did the Saudis give any hint today of a shift in tone. Instead there was the usual line about supply and demand being relatively balanced. The interesting question is when the US will step up pressure on the Saudis to increase production. One suspects there's not long to wait.